TechSpectra Interview Questions and Answers

OOPS concepts are fundamental to Java programming. They are used in various projects to achieve code reusability and maintainability.

• Encapsulation: Used to hide implementation details and protect data integrity.

• Inheritance: Used to create a new class from an existing class, inheriting its properties and methods.

• Polymorphism: Used to perform a single action in different ways, such as method overloading and overriding.

• Abstraction: Used to provide a simplified view of complex sy...read more

SQL joins are used to combine data from two or more tables based on a related column.

• Inner join returns only the matching rows from both tables

• Left join returns all rows from the left table and matching rows from the right table

• Right join returns all rows from the right table and matching rows from the left table

• Full outer join returns all rows from both tables

• Cross join returns the Cartesian product of both tables

Spring framework was used extensively in the project for dependency injection and MVC architecture.

• Used Spring Boot for easy setup and configuration

• Implemented Spring Security for authentication and authorization

• Utilized Spring Data JPA for database operations

• Used Spring MVC for handling HTTP requests and responses

• Implemented Spring AOP for logging and exception handling

Hibernate ORM maps tables in database using annotations or XML files.

• Use @Entity annotation to map a class to a table

• Use @Table annotation to specify the table name

• Use @Column annotation to map a field to a column

• Use @Id annotation to specify the primary key

• Use @GeneratedValue annotation to specify the generation strategy for primary key

• Use XML files for mapping if annotations are not preferred

Errors are unrecoverable, while exceptions can be handled.

• Errors are caused by the environment or JVM, while exceptions are caused by the application code.

• Errors cannot be handled, while exceptions can be caught and handled using try-catch blocks.

• Examples of errors include OutOfMemoryError and StackOverflowError, while examples of exceptions include NullPointerException and ArrayIndexOutOfBoundsException.

Connection pool can be created using libraries like Apache DBCP or HikariCP.

• Choose a connection pool library based on your requirements.

• Configure the pool size, maximum connections, and other settings.

• Create a data source object and set the connection pool properties.

• Use the data source object to get connections from the pool.

• Close the connections after use to return them to the pool.